The invention relates to a wheel motor traction assembly for use on a light duty vehicle adaptable for electric traction, the wheel motor traction assembly packaged to fit within a light duty vehicle wheel cavity and having mounting structure for vehicle chassis components which integrates vehicle braking, suspension and steering functions.
The use of wheel motors on a vehicle allows for precise control of power in and out of each wheel individually, which may result in increased traction control, improved drivability, handling and braking. It may be desirable to use wheel motors in vehicles that are adaptable for electric traction, such as vehicles with an electric battery power supply, a fuel cell, or hybrid combinations of a fuel cell, an electric battery power supply or an internal combustion engine. A reduction in tire slip losses achieved through the use of wheel motors may result in improved fuel economy. The use of wheel motors may result in improved vehicle packaging by conceivably eliminating the need for an inboard motor with gear reduction, drive shafts, motor mounts, and a differential. Designing a wheel motor with sufficient continuous and peak power capabilities to drive a light duty vehicle while minimizing size, weight and total unsprung mass (i.e., mass axially outward, or on the tire and wheel side, of the vehicle suspension system) has proven to be an ongoing challenge. Standard light duty vehicle wheel space limitations, requisite strength to withstand vehicle chassis loading and sufficient connectability to vehicle chassis components are further design considerations.
A wheel motor traction assembly for use on a light duty vehicle chassis includes a wheel and an electric motor that is operatively connected within a wheel cavity for drivingly rotating the wheel and has a nonrotatable motor housing. The motor housing is configured to substantially close an inward end of the inwardly open wheel cavity. The non-rotatable motor housing further includes an electrical connector and a structural connector, both being adapted for connecting the wheel motor traction assembly to the chassis. There is a suspension system structural connector and a steering system structural connector operatively connected to the motor housing configured for connecting the wheel motor traction assembly to a suspension system on a vehicle chassis and a steering system on a vehicle chassis, respectively. The motor housing is configured to bear vehicle chassis loads as the motor housing structurally interconnects the wheel with the chassis through the suspension system structural connector and the steering system structural connector.
The wheel motor traction assembly includes a rotatable wheel that has a radially outer tire support portion and a radially inner hub support portion that are cooperatively configured to define a wheel cavity. The wheel cavity is axially inwardly open with respect to the vehicle chassis and has inner and outer wheel parameters. The wheel is removably connected to the hub such that the wheel is rotatable with the hub. The wheel motor traction assembly also includes a rotor in the wheel cavity between the inner and outer wheel parameters. The rotor is operably connectable to the hub support portion for drivingly rotating the wheel. There is a non-rotatable stator in the wheel cavity between the inner and the outer wheel parameters for drivingly rotating the rotor. The rotor and the stator together are a motor.
A rotatable brake disc is operatively connected to the wheel and to the rotor, and a brake caliper in the wheel cavity is releasably connected to the motor housing, the brake caliper being adapted for selectively applying force to the brake disc. The brake disc is mechanically coupled with the hub. In one embodiment, the brake caliper is operably connectable and responsive to an hydraulic brake line on the chassis and configured to apply force to the brake disc in response to an hydraulic force on the hydraulic line. The invention includes a motor, which includes the rotor and the stator. In one embodiment, the motor is configured for regenerative braking. An embodiment of the invention also includes a mechanical parking brake caliper in the wheel cavity releasably connected to the motor housing and operably connectable to a park brake cable on the chassis.
The wheel motor traction assembly further includes a hub subassembly including a stub shaft, also referred to as a shaft, a hub rigidly connected to the stub shaft and removably connected to the rotor and to the wheel such that the hub and the stub shaft rotate with the rotor and the wheel, a shaft housing and a shaft bearing operatively connected to the stub shaft wherein the wheel and rotor rotate about the shaft bearing. The stator and the shaft housing are operatively connected and stationary with respect to the motor housing. The stub shaft, the rotor and the hub are rotatable with respect to the motor housing such that the bearing serves as a bearing for the rotor and for the wheel, and the motor, the hub subassembly and the motor housing substantially fit within the inner wheel parameter and the outer wheel parameter. The hub subassembly may further include a speed sensor and a position sensor located in the wheel cavity and operatively connected to the hub.
The wheel motor traction assembly includes a sealed power cable fitting operatively connected to the stator and to the motor housing, and adapted for connecting the stator to a power cable on the chassis.
The wheel motor traction assembly includes a wheel motor. The wheel motor is a compact disc-like axial flux motor for assembly within the vehicle wheel cavity. The wheel motor includes the non-rotatable motor housing, wherein the motor housing is configured as a disc that is sufficiently expansive to close the wheel cavity. The motor housing is sufficiently structural to at least partially support a vehicle chassis. The wheel motor includes the suspension system structural connector, also referred to as a vehicle suspension control arm pickup portion, on one side of the motor housing and the brake caliper on the other side of the motor housing. The motor stator is operatively connected to the motor housing. The wheel motor includes the rotatable hub and shaft wherein the hub and shaft are rotatably supported by the motor housing and are adapted for mounting the vehicle wheel. The wheel-motor includes the brake disc and the motor rotor wherein the brake disc and motor rotor are connected to the hub and shaft for rotation therewith. The brake disc is operatively connected to the brake caliper and the motor rotor is operably connectable to the stator. The wheel motor further includes a sensor connector port and a lower suspension control arm ball joint, also referred to as the lower suspension system structural connector, both located on the same side of the motor housing as the suspension control arm pickup portion.
The above objects, features and advantages, and other objects, features, and advantages, of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.